1. Field of the Invention
The present invention relates to a probe for laser irradiation, which is used in a medical laser device for performing laser treatment by irradiating a human being or an animal with laser light or beams.
2. Description of the Related Art
With the recent advance of science and technology, applications of laser light are being developed rapidly in the field of medical treatment. Especially, internal laser treatment to be performed or provided in combination with the utilization of an endoscope is expected to come into widespread use in the future, because the internal laser treatment permits a patient to be treated without an incision and relieves a burden imposed on the physical strength of a patient. Hereinafter, a photodynamic therapy (hereunder abbreviated as PDT), which utilizes medicine in combination with laser light, will be described.
This PDT is a treatment of a focus or nidus such as a tumor, to be performed by preliminarily accumulating photosensitive materials, which have specific affinity to the tumor and further have photochemical reaction characteristics concerning a cellulicidal action and fluorescence caused by optical excitation, on the focus and by thereafter irradiating the photosensitive materials with light, which can be absorbed by the materials, to thereby pump or excite the photosensitive materials and to consequently generate active oxygen. FIG. 8 illustrates a laser irradiation probe of the side irradiation type that is described in the Japanese Patent Laid-open No. 63-318933/1988 Official Gazette. As shown in this figure, a conical light diffuser (namely, a conical pointed light diffuser) B made of a transparent material, to the surface A of which a scraping process or a surface roughening process is applied, is attached to a light diffuser or end portion of a light-guide (optical) fiber. With this structure, laser light emitted from the light-guide fiber passes through the inside of the light diffuser B and then reaches a side surface of the light diffuser B. As shown in FIG. 9, the surface A of the light diffuser has an uneven structure. Thus the laser light is reflected at an irregular angle in dependence on the structure of the surface where the laser light has reached, as indicated by arrows in this figure. Incidentally, reference character M denotes a tissue to be treated.
However, in the case of the aforementioned conventional probe, when a laser treatment is performed by inserting the light diffuser B thereof into an internal nallow affected part or a diseased part which is in a stenosed state, namely, the tissue M to be treated, the roughened part of the surface of the light diffuser B is stained with a humor or an internal accretion. Thus, the transmissivity, at which the laser light is transmitted, of this part of the conventional probe is deteriorated. Further, the diffusibility, by which the laser light is diffused, of this part is degraded. Consequently, the conventional probe has faced problems in that the irradiation of laser light cannot be performed in an established manner and in that a same laser irradiation probe cannot be used repeatedly.
Moreover, the conventional probe has an omnidirectional irradiation structure. Thus, the conventional probe further has encountered another problem in that even a tissue, which does not need to be irradiated with laser light, is also irradiated with laser light.
The present invention is directed to resolving the problems which the conventional probe has faced.
It is, accordingly, an object of the present invention to provide a laser irradiation probe which can realize accurate and efficient treatment and can be used repeatedly.